The present invention relates generally to loose fill thermal insulation blowers, and in particular to a vertically oriented air lock type system with means for metering the rate at which pieces of thermal insulation are fed to the air lock.
Loose fill thermal insulation blowers in use today generally fall into one of two categories, through-the-blower systems and air lock systems. In through-the-blower systems, the insulation bale must normally be torn apart by hand and then further ripped into relatively small pieces by agitating knives or fingers that are powered by the apparatus. The thermal insulation pieces are then fed into the suction side of a high-speed (10,000 rpm) centrifugal blower. The delivery of the thermal insulation material to the desired location is accomplished via a flexible hose connected to the outlet of the blower apparatus. The rate of delivery of insulation for through-the-blower systems is generally controlled by the size of the blower, the centrifugal impeller design, the amount of air allowed to enter at the suction air gate, and/or the amount of insulation allowed to enter at the suction material gate.
Such systems are normally very adaptable to different blowing situations such as attic blowing, wall cavity blowing, and wet adhesive spraying of insulation onto a free-standing surface; however, through-the-blower systems suffer from a number of disadvantages, not the least of which is that the system is generally maintenance intensive and requires relatively large amounts of power to operate. Because all delivered material must go through the centrifugal impeller of the blower, an operator may inadvertently feed rocks, dirt, metal particles, cloth, etc. which can potentially do extensive damage to the impeller. Even if no foreign material is introduced to the system, the wear of the impeller is rapid and a continual maintenance concern. Finally, through-the-blower systems simply cannot achieve the high delivery rates of insulation required by many users, such as by commercial contractors.
In air lock systems, the insulation bale is also first torn apart by hand, then further ripped apart by agitating knives or fingers, and finally is fed into a rotating air lock. The pressure side of the blower is connected to one side of the air lock, and a flexible delivery hose is connected to the other side to deliver the insulation to the desired location. The rate of delivery of insulation in air lock systems is generally controlled by changing the speed of rotation of the air lock, changing the speed of the blower, and/or by adjusting the amount of insulation material allowed to enter the air lock through the material gate. These systems usually have the capability of high delivery rates, which can be as high as 3,000 pounds of insulation per hour. However, air lock systems in present use do not generally adapt well to blowing in enclosed spaces, such as wall cavities, because the required small diameter delivery nozzle places too tight a restriction on the system. It is also difficult in air lock systems to deliver the required three pounds per cubic foot of packed density that is necessary in order to prevent insulation settling within the wall cavity. Air lock systems are also usually relatively heavy, are not very portable and generally have high initial costs. Insulation blow density for open insulation blowing, such as in attic spaces, is generally not as good as through-the-blower systems because the material is not being fluffed by the high velocity impeller of a blower.
What is needed is a low-weight thermal insulation blower that is sufficiently portable to easily fit through a standard doorway, has relatively low power requirements at full load conditions, requires no hand shredding, has the capability to deliver high material rates, and has the flexibility to work equally well in closed blowing situations, such as into walls, and opening attic-type blowing situations.